Introduction of Open Web Steel Joist, Deck and Composite Steel Joist

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Introduction of Open Web Steel Joist, Deck and
Composite Steel Joist

• ENCE710 Advanced Steel Structures
• C. C. Fu, Ph.D., P.E.
• Department of Civil Environmental Engineering
• University of Maryland
• College Park, MD

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SJI Recommended Code of Standard Practice for
Steel Joists and Joist Girders

• 1.4 DESIGN
• In the absence of ordinances or specifications to
  the contrary, all designs prepared by the
  specifying professional shall be in accordance
  with the applicable Steel Joist Institute
  Specifications and Load Table of latest adoption.
• 1.5 RESPONSIBILITY FOR DESIGN AND ERECTION
• When material requirements are specified, the
  seller shall assume no responsibility other than
  to furnish the items listed in Section 5.2 (a).
  When Material requirements are not specified, the
  Seller shall furnish the items listed in Section
  5.2(a) in accordance with applicable Steel Joist
  Institute Specifications of latest adoption, and
  this code. The Seller shall identify material by
  showing size and type. In no case shall the
  Seller assume any responsibility for the erection
  of the item furnished.

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Example of a Typical Floor Plan
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Joist Roof Load Path by Tributary Area
Roof deck transfers load to supporting joists.
Each joist supports an area equal to its span
times half the distance to the joist on either
side.
Load rests on roof deck
The joists transfer their loads to the supporting
truss girders.
The pier supports half the area supported by the
truss girder plus area from other structural
elements that it supports.
Each truss girder supports an area equal to its
span times half the distance to the girder on
either side.
The truss girders transfer their loads to the
supporting piers and columns.
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Steel Construction
or Joist Girder
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Open Web Steel Joists

• Steel joists are prefabricated lightweight
  trusses that are available in different series
• K series- 8 through 30 in 2 increment with 64
  designations clear spans to 60 (short span)
• (KCS series for special loading conditions)
• LH series 18 through 48 clear spans to 96
  (long-span)
• DLH series 52 through 72 clear spans to
  144 (deep long-span)
• For Composite Steel Joists, see David Samuelsons
  paper (AISC Engineering Journal, 3rd Quarter,
  2002)

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Open Web Steel Joist - 2
Designation 12K4 12 depth in inches K
joist series 4 designation within series (the
higher the number, the heavier the joist)
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Pitched Top Chord Joists
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Span Length
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Joist Girders

• Designed to carry the regularly spaced,
  concentrated loads consisting of the end supports
  of joists.
• Designation 48G 8N 8.8K
• 48G depth in inches
• 8N number of joist spaces
• 8.8K load on each panel point in kips

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Joist Girder - 2
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Joist Girder - 3
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Bridging
Horizontal Bridging (for span L lt 60)
Diagonal Bridging (for span L gt 60)
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End Anchorage - Beam
Wall anchors
Beam anchors
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Standard Load Table/Open Web Steel Joists,
K-Series
Black figures TOTAL safe uniformly distributed
load-carrying capacities (lb/ft) Red figures
LIVE loads (lb/ft) which will produce an
approximate deflection of L/360.
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Metal Decking

• Metal decking is used for floor and roof
  applications.
• Determine type of decking, thickness, gage of
  metal, finish required, and method of attachment
• Unit square (100 sf)

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Steel Joist and Metal Deck
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Steel Deck Units
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Finish, Depths, Gages and Grades

• Finish
• unpainted
• primed
• painted
• galvanized
• Depths from 9/16 to 7.6
• Gages from 10 (0.135) to 28 (0.0149)
• Grades Yield points from 33 to 80 ksi
• (See Richard Heaglers paper Form Deck A
  Versatile Family of Products, by AISC, 2003)

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Quantity takeoff

• Determine the LF of each different type of
  joist, use manufacturers table to find the
  weight per ft and total weight.
• Note type and number of accessories
• bridging (diagonal or horizontal)
• end anchorage (beam or wall)